This invention relates to magnetohydrodynamic (MHD) energy conversion devices, i.e., energy conversion devices capable of converting heat directly into electrical energy.
As is known in the art, electricity can be produced in a MHD (magnetohydrodynamic) energy conversion device wherein a working fluid in the nature of a plasma, i.e., an electrically-conductive ionized gas flows through a magnetic field perpendicular to the direction of plasma flow. This action generates an electric current in the ionized gas which can be tapped by electrodes located in the magnetic field and in contact with the moving plasma. The stronger the magnetic field and the higher the temperature and velocity of the ionized gas, the greater is the relative amount of electricity that can be extracted from the MHD energy conversion device. Examples of MHD devices used to convert solar and laser energy into electricity are illustrated and described in U.S. Pat. Nos. 4,191,901 and 4,275,318.
Electromagnets have proven impractical for use in MHD energy conversion devices because they require electricity to stay cool in order to sustain high magnetic flux densities necessary for efficient production of electrical energy. Prior art MHD energy conversion devices have been limited to the use of magnets having magnetic flux densities of no greater then 1-2 tesla which has made such energy conversion devices unsuitable for use in electric power generation for residential, remote, portable, commercial and industrial applications.